11.   The barriers were solid, but only until the mid-fifties.

12.   The legal barriers are presently insuperable.

13.   The simplest protective barrier is a geographical one, namely to conduct the training away from other centres of activity within the organisation.

14.   There are barriers to a free movement of people from areas of high to low population pressure.

15.   This barrier is a complex structure that prevents many drugs and chemicals in the blood from entering the brain.

16.   Unfortunately, their trade barriers are such that nobody can get inside and buy anything.

17.   The barriers are lethal to fish trying to swim upstream.

18.   Capital markets are perfect in that there are no barriers to exit or entry and information is freely available to all.

19.   This is in support of the notion that deranged intestinal barrier is not primary to the allergic state, but rather secondary to the hypersensitivity reaction.

20.   These barriers are especially strong for women and younger people.